Cooling System Pressure Test

WARNING: This page is about a different car, the 2012 Ford Fiesta. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.

NOTE: Vehicles have the pressure relief cap on the degas bottle and no radiator cap

Turn the engine OFF.
Check the engine coolant level. Adjust the coolant level as necessary.
Disconnect the coolant return hose located at the rear of the engine

Fig 1: Locating Coolant Return Hose At Rear Of Engine
Courtesy of FORD MOTOR CO.
Attach the D-Gas Adapter inline with the overflow hose and install the Radiator Tester to the quick connect fitting of the D-Gas Adapter.

Fig 2: Installing Radiator Tester To Quick Connect Fitting Of D-Gas Adapter
Courtesy of FORD MOTOR CO.

NOTE: Do not pressurize the cooling system beyond the maximum pressure listed in the SPECIFICATIONS or cooling system components may be damaged.

NOTE: If the plunger of the pressure tester is pressed too fast, an incorrect pressure reading results.

Slowly press the plunger of the pressure test pump until the pressure gauge reading stops increasing and note the highest pressure reading obtained. If the pressure reading exceeds the maximum cap pressure listed in the specifications table, install a new pressure relief cap.
If the system does not hold pressure, remove the pressure relief cap and wash it in clean water to dislodge all of the foreign material from the gasket. Check the sealing surface in the filler neck of the degas bottle for nicks or cuts. Use fine sandpaper or emery cloth to remove nicks and cuts. Place a shop cloth in the filler neck to prevent debris from falling into the degas bottle. If nicks or cuts are too deep to remove, install a new degas bottle. Install the pressure relief cap.
Pressurize the engine cooling system as described in Step 4. Observe the gauge reading for approximately 2 minutes. Pressure should not drop during this time. If the pressure drops, inspect for leaks and repair as necessary.
If no leaks are found and the pressure drops, the pressure relief cap may be leaking. Install a new pressure relief cap and retest the system.
If no leaks are found after a new pressure relief cap is installed, and the pressure drops, the leak may be internal to the engine. Inspect the coolant for engine oil and the engine oil for coolant. Refer to ENGINE SYSTEM - GENERAL INFORMATION to diagnose the engine.
Release the system pressure by loosening the pressure relief cap. Check the coolant level and adjust as necessary.